IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specification for implementing wireless local area network (WLAN) communication, in the unlicensed (2.4, 5, and 60 GHz) frequency bands. Alternatively, Bluetooth is a set of media access control (MAC) and physical layer (PHY) specification for implementing personal area network (PAN) or point to point (P2P) communication, in the unlicensed (2.4) frequency band. The standards and amendments provide the basis for wireless network products using the IEEE 802.11 and Bluetooth frequency bands. IEEE 802.11 and Bluetooth plays an important role in the growing application of Indoor/Outdoor positioning. Direction fining (DF) positioning is achieved from either Angle of Departure (AoD) or Angle or Arrival (AoA). In AoD, the transmitter transmits through multiple antennas and the receiver (tracker) resolves the angle of departure relative to the antenna platform of the transmitter based on the received signals. In AoA, the receiver (tracker) employs multiple antennas to receive signal and resolves angle of arrival relative to its own antenna platform orientation. In both AoD and AoA, only one device with multiple antennas or antenna elements is needed, and only one-way signal transmission is required.
Multiple antenna elements on an antenna platform can be used to estimate AoA or AoD based on the phase difference and signal strength observed from the received signal at the multiple antenna elements or signals received from the multiple antenna elements. In the antenna array based DF system, the array response of all directions, which are often measured in chamber, needs to be pre-known. For example, the current Indoor Positioning Service 1.1 (high accuracy indoor positioning) requires transferring of antenna pattern database from the transmitter to the tracker (e.g., the Bluetooth (BLE) device). The volume of the database is 2M bytes, which results in high transmission overhead and increase device storage size. Even after compression, the volume of the database is still quite large (˜50 kbytes). The database is used by the receiver to correlate with the signal samples and obtain the AoA and AoD information.
Based on signal model, the BLE location can be solved using conventional AoD algorithms if the antenna platform information is known. Therefore, it is desirable to have an alternate simplified antenna platform format to enable the use of conventional AoD algorithms such as Bartlett beamformer, MUSIC, etc.